Field of the Invention
The invention relates to a touch apparatus, and more particularly to an optical touch apparatus and a width detecting method thereof.
Description of Related Art
Generally, in an optical touch screen, a plurality of optical lenses are disposed on an edge of the screen to capture images of operation of a touch object on the screen. Next, in the captured images, a shadow cast by the touch object on an optical touch plane due to a shielding effect or a bright spot generated due to a reflection effect is analyzed, so as to obtain relative angles between the touch object and the optical lenses. Finally, a precise position of the touch object is obtained through triangulation based on a distance between the optical lenses.
The optical lenses are usually fixed on both ends of an optical touch apparatus, and the distance between the optical lenses is usually constant. Thus, the optical touch apparatus can only be applied to a screen having a fixed size. To enable application of the optical touch apparatus to screens of different sizes, the optical touch apparatus may be designed to be expandable. In other words, the distance between the optical lenses in the expandable optical touch apparatus is adjustable. However, a user has to adjust a width of the expandable optical touch apparatus according to the screens of different sizes, and to manually measure the distance between the optical lenses. Then, the user needs to manually input the measured distance between the optical lenses to the expandable optical touch apparatus, so as enable the expandable optical touch apparatus to precisely calculate a position of the touch object. Accordingly, extreme inconvenience in use is caused.